1. Field of the Invention
The invention relates to a method for compensating for wear of a finishing tool in the finish machining of workpieces, in which a reference surface layer of the workpiece is removed by a feed motion of the finishing tool controlled by an NC feed program, wherein the NC feed program re-calculates the feed path for the next workpiece by comparing the actual wear of the prior workpiece to a known empirical wear trend line and compensates through an adjustment of the feed motion of the NC feed program.
2. Description of the Related Prior Art
Finish machining of a workpiece corrects dimensional deviations and non-round regions of a workpiece and produces a smooth surface, which is distinguished through a low depth of roughness. The term “finishing work” includes, in particular, fine grinding and honing methods. Finishing tools can include, for example, abrasive belts, honing stones, rotating grinding cup wheels, and the like. The suitable finishing tool is selected according to the workpiece to be processed. Workpieces can include, for example, brake disks, connecting rods, crankshafts and camshafts, toothed racks, gears, anti-friction bearings, also medical prosthetics and workpieces made from ceramic, glass, or plastic.
The finish machining is performed through a relative motion between a workpiece surface and a finishing tool, wherein the relative motion can be divided into a motion essentially parallel to a surface of the workpiece and a feed motion between the workpiece and finishing tool. By controlling the feed motion, a given workpiece dimension can be achieved, wherein, however, a change in the finishing tool, due to wear, is to be taken into account. The relative motion between the finishing tool and the workpiece surface can be achieved by driving the finishing tool and/or the workpiece.
A method for compensating wear with the features described above is known in the prior art. In this prior art method, wear of the finishing tool is extrapolated with reference to a typical empirical wear trend starting from a new finishing tool, and the feed motion is adjusted accordingly by the NC feed program. Because irregularities in the quality of the finishing tool and workpiece are not taken into account at first, the wear compensation is imprecise, wherein systematic deviations add up over the entire service life of the finishing tool. After finish machining, the wear trend can be checked with reference to an exact measurement of the workpieces and adjusted if necessary. As long as the measurement is performed directly after the finish machining, the wear trend for a specific finishing tool can also be checked during operation and, if necessary, corrected. The realization of such post-process measurement control, however, is relatively complicated, time consuming, and expensive.
From experience, it is further known to determine the wear of the finishing tool directly during the finish machining, for example, with a measurement sensor, and to adjust the feed motion as a function of measurement sensor reading by means of the NC feed program. For precise consideration of the wear determined by the measurement sensor, a very low workpiece tolerance can be achieved, wherein the described in-process measurement control is complicated and very expensive.